Glenbrittle, Isle of Skye, August

The Fairy Pools at Glenbrittle on the Isle of Skye. Photograph: Dave Nash

I am standing half-naked on the edge of a crystalline pool in a remote Scottish glen, toes numb from a tentative dip. My family shouts encouragement, like the baying crowd at the Colosseum, cajoling me to jump. There is no going back.

Rewind two months and a snatched conversation on the radio extolling the pleasures of swimming "wild" in Britain's rivers and lakes. "The best?" asks the interviewer. The Fairy Pools of Skye, comes the unequivocal reply. An evocative description follows, but before the speaker has finished I have made a decision: I too will swim the pools.

August. Glenbrittle, Isle of Skye. The midday heat has despatched even the most sadistic of midges deep into the heather. The Black Cuillins rear up in front of us, a natural amphitheatre framing the rowan trees that map out the run of the pools. "Are there really fairies here, daddy?" asks our youngest.

"Freezing," a rotund Scot snarls through chattering teeth. How long did you last? I ask. His face softens and he grins: "Long enough to resurface." Enthusiasm is draining.

The pools do not disappoint. Their deep, emerald clarity delivers the awe factor I had hoped for. We shed our clothes and splash in the shallows and throw pebbles that meander down into the deep. But the water is cold. So cold. The time has come, however, and I steel myself. To falter now is not an option: I've talked the talk too many times.

I jump, and for a micro-second I feel frozen, suspended above the water. Then an icy grasp rips through my body and I am reaching for the surface, hyperventilating. "Stay in the water," was the advice. One minute and your internal radiator kicks in. So I frantically dog-paddle, like a mongrel that has just discovered it is unable to swim.

The kids look anxious, so I mutter assurances, despite the voices in my head that scream at me to exit. I'm beginning to think I am too trusting of the advice when the most marvellous thing happens. My body warms. My strokes become smoother and my breathing settles. It has become, against all expectation, pleasurable.

The water is so pure, so invigorating, like bathing in chilled Evian. A submerged arch between pools presents an unmissable opportunity to gain some serious kudos with the kids. Likewise, the water is deep enough to accommodate leaps from the highest rocks. All of this accompanied with squeals and applause. Before long the whole family is gaining courage, and even the littlest is riding piggy-back across the water.

Late in the day, warm, exhilarated and bewitched, we wend our way back through the heather, leaving the pools for the fairies to enjoy in peace. Magical.